Comment on PCB Design Review Request: ESP32 Smart Relay Board
rufus@discuss.tchncs.de 1 year ago
I’d agree with the tip of that ground plane is close to the high voltage part.
The ULN2003A claims to have the flyback diodes and they’re connected.
I’m not an electronic expert myself. But I don’t get why the fuses are the way they are. Most of the times I see boards having one fuse and when it’s blown, the whole board is separated from electricity. You’re kind of splitting it up 3 ways.
Starfighter@discuss.tchncs.de 1 year ago
The main reason for splitting up the relays into two sets is that with 10A traces the connector pins would violate minimum separation distances. I would have to get even larger connectors. The ones in the design have 5 mm pitch.
I’m assuming the original board also did this for the same reason although their board is set up for 8 motors split into sets of 4.
I’ve also had some trouble sourcing a 10A fuse suited for inductive loads but I’m sure I could find one with some more time.
The whole board is on its own house circuit fused with a 16A breaker.
rufus@discuss.tchncs.de 1 year ago
Thanks for explaining. Yeah, I’m sure it’s pretty much alright with your circuit breaker. I suppose your main concern for having those fuses is so that those relais can’t start a fire once the current is between 10A and 16A for too long. I was just thinking about failure modes. And having something fail, the fuse blow and then half the board still has 230V feels a bit strange. But I guess it’s alright. I’m not an expert anyways.
I saw those PCB mounted 5V power supplies coming up in ESP32-projects before. I always thought they were some cheap chinese stuff and you shouldn’t trust them. But if they have a proper fuse inside and do proper 5V… Maybe I need to change my mind and start digging deeper.